Help with through DT on PC 4212

[jarhead]

Many of you here own a Porter Cable 4212 dovetail jig and hope that someone can help me out to solve my problem. I am cutting through dovetails and the drawer front does not line up with the side - they are shifted slightly.

Page 10 of the basic owners manual tells you to center the workpiece between the farthest finger to the left and the nearest finger to the left of the template (this is eyeballing it). I even go as far as using a caliper to make sure there is an equal distance between the fingers. Thinking about it, once the tails board is centered and the left offset guide is set and tightened, it should not matter if it's not perfectly centered. If it's off center by, say 1/64th, then when the pins board is registered against the offset guide and routed, it also should be off center by the same amount and the boards should line up.

Is it possible that the template is defective?

[jarhead]

Anybody?

[LarryG]

Is it possible that the template is defective?

Possibly. I've not tried thru DTs with my 4212 yet, but if the slots for the tails and pins are not perfectly aligned with each other across the template, this kind of misalignment could result.

But I think a more likely possibility is that the bit is shifting relative to the router's centerline when you change from the tails setup to the pins setup. This could be related to the height setting, or the change of guide bushings (I'd bet on the latter).

A workaround would be to cut your drawer body pieces slightly oversize, and take them down to final size after you've cut the DTs.

[jarhead]

Possibly. I've not tried thru DTs with my 4212 yet, but if the slots for the tails and pins are not perfectly aligned with each other across the template, this kind of misalignment could result.

But I think a more likely possibility is that the bit is shifting relative to the router's centerline when you change from the tails setup to the pins setup. This could be related to the height setting, or the change of guide bushings (I'd bet on the latter).

A workaround would be to cut your drawer body pieces slightly oversize, and take them down to final size after you've cut the DTs.

Larry,
That's an interesting observation that I didn't think about. For this task I have dedicated two routers; one for each bit. I did use a centering cone to make sure that the guide bushing was centered. I guess there is still room for error.

If I were to cut the drawers oversized and cut them to final size after the DT's were routed, I'd have to carefuly sneak up on the cuts for the half pins to line up. I guess that's a good alternative.

[Stormbringer]

Alex,

Here's something I spotted from one of the reviews on Amazon.


I am not new to woodworking, but I am new to making Dovetails. I've watched Norm make them, and it didn't look very difficult to do. After reading all the reveiews on it, I'm am embarassed to report how much difficulty I had making drawers. After many hours, a call to Porter Cable and help from my wife, I was finally successful. A video showing how to make a completed drawer from start to finish would have helped. The video that I saw on the internet only showed the partial making of a drawer. It would have been helpful if they had shown that you line up your wood on the left side of the jig, cut your dovetails, and then line up the other end of the board on the right side and finish cutting the dovetails. I plan to make a lot of drawers using this jig now that I have figured it out. I'm glad my wife bought it for me.




Also, did that scan of the WOOD dovetail problem chart help at all? Maybe it would help with your current problem?

http://www.bt3central.com/attachment...7&d=1142988270

Good Luck,
Greg

[jarhead]

Alex,

Here's something I spotted from one of the reviews on Amazon.


...After many hours, a call to Porter Cable and help from my wife, I was finally successful. A video showing how to make a completed drawer from start to finish would have helped. The video that I saw on the internet only showed the partial making of a drawer. It would have been helpful if they had shown that you line up your wood on the left side of the jig, cut your dovetails, and then line up the other end of the board on the right side and finish cutting the dovetails. I plan to make a lot of drawers using this jig now that I have figured it out. I'm glad my wife bought it for me.




Also, did that scan of the WOOD dovetail problem chart help at all? Maybe it would help with your current problem?

http://www.bt3central.com/attachment...7&d=1142988270

Good Luck,
Greg

Greg,
Honestly, it makes no sense whatsoever what this guy is saying about cutting the DT on the left and then aligning the board on the right. The manual states no such thing. I spoke with Porter Cable and explained how I cut the through DT and they said that I was doing it correctly.

I did see your the chart before - the "fix for misaligned boards is blowing out the dust and making sure the board is flush against the offset guide which I have checked.

Maybe I should do what the Amazon reviewer had done... ask my wife for help.

[sacherjj]

I initially ran into this. The problem is that your reference isn't exactly centered. It doesn't have to be though. The tails piece can be cut facing either direction in the jig. However, it will only line up both directions if you are perfectly centered. I forget if it was outside or inside facing the jig, but I believe it was the opposite of the pins board (which can only go one way.)

The extra manual from the Porter Cable site really helped. I marked my first test piece with the side that was facing the jig. When I reversed the next piece, everything matched up.

[jarhead]

...I think a more likely possibility is that the bit is shifting relative to the router's centerline when you change from the tails setup to the pins setup. This could be related to the height setting, or the change of guide bushings (I'd bet on the latter).

Larry,
I looked at the router that I set up to cut the pins with and the straight bit was definitelly not centered in the bushing. I did use a centering cone when I set it up. In this case, when the pins are routed, they are not centered between the fingers which will explain the misalignment.
I leave my router standing on its head on the workbench. Sometimes my son reaches to get things off the shelf and knocks it down (and leaves it on its side). I bet those couple of times that he knocked it down, the baseplate may have shifted slightly.

[L. D. Jeffries]

Don't know if this is the problem but I found thru experience that using a bit centering pin to align the base plate can be a help. I was making some inlays with my router and couldn't unerstand way inlayed pieces wern't lining up. Did a re-alignment on the base plate and cured the problem. It might be a useful thing to do just because! Especially after reading that the router may have been tipped over. My 2cts worth.

[jarhead]

I found a site that reviews PC 4112 half-blind DT jig may be helpful to others. In this particular case, "Template Guide Bushings" section should be of interest. This Saturday I will recenter the guide bushing and report my results.

[jarhead]

This Saturday I will recenter the guide bushing and report my results.

Bingo! Centering the bit in the guide bushing solved the problem.